The present invention relates to integrated circuit (IC) package testing and more particularly, to testing the electrical characteristics of an IC package and its interconnect structures.
Predicting the performance of high speed integrated circuits requires accurate measurements of the electrical characteristics of the package and the interconnect structures which interface both the integrated circuit with the package and the package with an external board. Typically, time domain reflectometry and network analysis measurements are performed to characterize the electrical performance of the package which can dominate the performance limits of high speed integrated circuits.
Electrical characteristics of packages, which are frequently the subject of measurement, include cross-coupling with neighboring lines, spectral dispersion, electrical resonances, and loss by radiation into the surrounding dielectric.
The measuring stations of the prior art are traditionally constructed to support a package under test in a horizontal position. This arrangement provides direct physical access to only a single side of the package. Simultaneous access to both sides of a package is unavailable in these test stations. Looping fixtures are often required to achieve through-package electrical characterization. Also, specially constructed mounting cards are sometimes used which not only hold a package but also attempt to provide all connections on the top of the card for easy physical access and probing. The use of looping fixtures and other package mounting cards introduce effects into the measurement data which are not due to the package or its interconnects. These effects must, themselves, be determined and either compensated for or modeled into the final analysis of the data. Regardless, of how they are handled, these effects degrade both the efficiency and accuracy of the resulting package electrical characterization.
The present invention addresses the needs for a method and apparatus to measure the electrical characteristics of an integrated circuit package in an efficient, precise and accurate manner.
The integrated circuit package test station of the present invention supports an integrated circuit package under test in a vertical orientation thereby allowing simultaneous access to both sides of the package. Probe assemblies are utilized on both sides of the package to increase the efficiency and simplicity of performing electrical characterization of the integrated circuit package. The integrated circuit package support as well as the probe assemblies are adjustably positioned to allow accurate and precise measurements of through-package electrical characteristics. To aid in positioning the test equipment, a dual-display image magnification system is used in certain embodiments which provides images of both sides of the IC package simultaneously.
The needs are also met by embodiments of the present invention which provide an electrical characterization of an IC package based on measurements from a first probe assembly which electrically probes a first side of an IC package and a second probe assembly which electrically probes a second side of the IC package, and a vertical package holder which supports the IC package in a substantially vertical orientation to allow simultaneous access to the first and second sides of the IC package.
The needs are further met by embodiments of the present invention which probe an IC package by supporting the IC package vertically wherein a first and second side of the IC package is simultaneously accessible, probing the first side of the IC package, probing the second side of the IC package, and determining an electrical characterization of the IC package based on the probing of both sides.
The foregoing features, as well as other aspects and advantages, of the present invention, will become more apparent from the following detailed description, claims and drawings.